Directed Objectives: Exam VI

Question 1

Sensors For Visceral Pain Pg. 466-467

Answer 1

• Visceral senses provide information about various internal organs and consist primarily of pain and pressure.
• Two Types Sensors For Visceral Pain:
• Pain which is a nocioreceptor.
• Pressure which is a mechanoreceptor.

Question 2

Meissner Corpuscle Pg. 468-469

Answer 2

• Meissner corpuscles, tactile corpuscles, are distributed throughout the dermal papillae and are involved in two-point discrimination.
• Structure:
• Several branches of a single axon associated with specialized Schwann cells and surrounded by a connective tissue capsule.
• Function:
• Two-point discrimination
• Two-point discrimination (fine touch) is the ability to detect simultaneous stimulation of Meissner corpuscles in two distinct receptor fields by touching at two points on the skin.
• The distance between two points that a person can detect as separate points of stimulation differs for various regions of the body.
• Extra Information
• Meissner corpuscles are numerous and close together in the tongue and fingertips but are less numerous and more widely separated in other areas, such as the back.

Question 3

Free Nerve Endings (Job) Pg. 467-468

Answer 3

• The simplest and most common sensory receptors.
• Free Nerve Endings which are relatively unspecialized neuronal branches similar to dendrites.
• Free nerve endings are distributed throughout most parts of the body and are especially abundant in epithelial and connective tissues.
• Receptors are responsible for a number of sensations, including pain, temperature, itch and movement.
• Free nerve endings responsible for temperature detection respond to three types of sensations:
• Cold Receptors
• Warm Receptors
• Pain Receptors
• Overall Function
• Pain, itch, tickle, temperature, joint movement, and proprioception

Respond to painful stimuli, temperature, itch, joint movement, and proprioception.

Question 4

Picture (Liver, Kidney & Urinary Bladder) Pg. 560 & 563

Answer 4

Review Pg. 560 & 563

Question 5

Photoreceptors Pg. 467

Answer 5

• Photoreceptorrs respond to light striking the receptor cells and are necessary for vision.
• Cells are in the retina that begin the processing of seeing.
• Absorb and convert light into electrical signals that are sent to the brain.
• These signals are sent to other cells in the retina and ultimately through the optic nerve to the brain where they are processed into the images we see.
• Two General Types: Cones and Rods

Question 6

Chemoreceptors Pg. 467

Answer 6

*Respond to chemicals.

• Smell and taste depend on chemoreceptors.
• Interact with chemicals in our blood and in what we smell and eat.
• Location: Taste Buds, Olfactory Bulb, Hearts and Heads, Peripheral Chemoreceptors and Central Chemoreceptors
• Your sense of taste comes from taste buds on your tongue.

*Your sense of smell comes from your olfactory bulb. Olfactory bulb is an organ in your nose that has chemoreceptors
located on neurons in different zones that detect different types of odors.

• Chemoreceptors are also found in our hearts and heads.
• Example: If you’ve ever felt ‘short of breath’ because of exercise or nervousness, the chemo receptors in your body have detected that oxygen levels are too low or that carbon dioxide levels are too high.

*Conveyed to the brain using neurotransmitters, which are brain chemicals that transmit signals from one cell to another.

Question 7

Osmoreceptors G-17

Answer 7

*Receptor in central nervous system that responds to changes in the osmotic pressure of the blood.

• Contribute to maintaining fluid balance in the body.
• Primarily found in the hypothalamus and kidneys.

*It is important to maintain this balance because changes could lead to water moving in or out of cells, affecting cell function and, in extreme cases of high osmolarity, causing cells to burst.

Question 8

Mechanoreceptors Pg. 467

Answer 8

*Respond to mechanical force such as compression, bending, or stretching of cells.

• Receptors in the skin and on other organs that detect sensations of touch.
• Designed to detect mechanical sensations or differences in pressure.

*Types of Mechanoreceptors: Senses of touch, pressure, proprioception, hearing , and balance all depend on a variety of mechanoreceptors.

Question 9

Thermoreceptors Pg. 467

Answer 9

• Respond to changes in temperature at the site of the receptor and are necessary for the sense of temperature.
• Thermoreceptors Example: Temperature
• Location:
• Located in the dermis, skeletal muscles, liver, and hypothalamus that area activated by different temperatures.

Notes: Free nerve endings only respond to 50-118 degrees Fahrenheit. Any lower or higher and the pain receptors take over.

Question 10

Picture of Sensory Nerves In Skin Pg. 468

Answer 10

Review Pg. 468

Question 11

Merkel Disc Pg. 468-469

Answer 11

• Merkel Disks, or tactile disks, are more complex than free nerve endings.
• Structure:
• Consists of flattened expansions at the end of axons; each expansion is associated with a Merkel cell.
• Receptors are distributed throughout the basal layers of the epidermis just superficial to the basement membrane and are associated with dome-shaped mounds of thickened epidermis in hairy skin.
• Function
• Light touch and superficial pressure
• These receptors can detect a skin displacement of less than 1mm (1/25 inch).

Question 12

Pacinian Corpuscle Pg. 468-469

Answer 12

• Pacinian Corpuscles, or lamellated corpuscles, are complex receptors that resemble an onion.
• A single dendrite extends to the center of each Pacinian corpuscles.
• Location: Within the subcutaneous tissue, where they are responsible for deep cutaneous pressure and vibration.
• Associated with joints help relay proprioreceptive information about joint positions.
• Structure
• Onion-shaped capsule composed of several cell layers with a single central nerve process
• Function
• Deep cutaneous pressure, vibration and proprioception

Notes: Pacinian corpuscles out side of articular capsules respond to acceleration and deceleration of joints during movement.

Question 13

Referred Pain Pg. 476

Answer 13

*A painful sensation of in a region of the body that is not the source of the pain stimulus.

• Most commonly, patients sense referred pain in the skin or other superficial structures when internal organs are damaged or flamed.
• This sensation usually occurs because both areas of the skin to which the pain is referred and the visceral area that is damaged are innervated by neurons that project to the same area of the cerebral cortex.
• The brain cannot distinguish between the two sources of painful stimuli, and the painful sensation is referred to the most superficial structures innervated by the converging neurons. This referral may occur because the number of receptors is much greater in superficial structures than in deep structures and the brain is more “accustomed” to dealing with superficial stimuli.
• Referred pain is clinically useful in diagnosing the actual cause of painful stimulus.

For example, heart attack victims often feel cutaneous pain radiating from the left shoulder down the arm.

Areas of Referred Pain on the Body Surface Chart is on Page 477.